Morgans wrote:

Wal-Mart, for one. It is billed as a license plate backup camera, or
something like that. It fits right over the plate bolt holes.

My son got one for easy hook-up of trailer towing. It works!

Best thing is it doesn't have to be HD or even SD, just so you have an
identifiable image. You can get a CMOS camera w/audio that transmits on
2.4GHz to a matching receiver, that has a/v outputs, for about $50, ordered
from Hong Kong on eBay. OK, laugh, I got one, and it works!! Just be
forewarned that you do NOT wack of the oversized coaxial connector to the
transmitter/camera that connects to a 9V battery, because that also has a 5V
regulator built in - which the assholes don't tell you, so if you downsize
to a resonable sized set of plugs, the camera gets fried... Don't ask....
Anyway, it is very easy to have a ultra compact, cheap video camera these
days... The most expensive item is the monitor, and even then you're
talking $100..